Fine-scale harbour seal usage for informed marine spatial planning.

Area of Science:

• Marine biology
• Conservation science
• Spatial ecology

Background:

• Harbour seal (Phoca vitulina) populations around Orkney, Scotland, have declined significantly (78% over 20 years).
• Declining seal populations have led to restrictions on tidal energy developments in the region.
• Accurate distribution data is vital for conservation and managing human impacts.

Purpose of the Study:

• To create high-resolution harbour seal usage maps for Orkney and the North coast of Scotland.
• To inform conservation strategies and assess the impact of commercial developments on harbour seals.
• To provide spatially explicit data for licensing and consenting processes.

Main Methods:

• Utilized telemetry data from 54 tagged harbour seals (2003-2015).
• Developed predictive habitat models (GAM-GEEs) to estimate seal density and predict space use.
• Combined density maps with terrestrial counts (2008-2015) to generate population-level usage maps with confidence intervals.

Main Results:

• Identified key predictors of harbour seal space use: distance from haul-out sites, sand proportion in seabed sediment, and annual mean power.
• Generated fine-scale harbour seal usage maps with confidence intervals for the study area.
• Demonstrated the utility of these maps for determining local abundance and assessing anthropogenic impacts.

Conclusions:

• High-resolution harbour seal usage maps are essential tools for conservation management.
• These maps facilitate the spatial assessment of commercial development impacts on protected species.
• Linking usage maps with individual-based models can predict impacts on seal movement and behavior.